That says the bag set off a bomb sensor. so who says it was the garlic paste? Is that a known sensitivity to the explosives wipes? Should I avoid Chinese and Thai before a trip to a secured facility where these explosives detectors are used?

Unrelated, but one time during a construction project, garlic crates were brought in to haul away some of the demolition debris. The work was done at night in an occupied building. Well, the next day, the entire wing was evacuated because they thought the smell was from a hazardous chemical leaking from the locked construction site. I showed them the chemical they thought it was- which was odorless, and not leaking. Just goes to say- what you can smell is significantly less hazardous than what you can't! (albeit a little more unpleasant...)

I've heard that once in a while golf clubs also set off the "swab test," or whatever that thing is called, because of the fertilizer left over from the grass. I wonder what other common items can set it off. Could be a fun experiment.

The airport was not totally evacuated. The CTX machine in that terminal is located in the ticketing lobby. The people in that area were sent outside while the crews inspected the bag. The security checkpoint remained and terminal remained open. AA ticketing was closed for that time. This was just a case of the machine giving a false positive. This was an unfortunate incident and surely a pain in the ass for everyone involved, but was handled by the book. As always the news reports make it sound worse than it actually was. Hopefully soon we will be able to get better equiptment so that this won't happen again.

Quoting PHLJJS (Reply 4):This was just a case of the machine giving a false positive.....Hopefully soon we will be able to get better equiptment so that this won't happen again.

Thanks for the info- yes, it sounded to me like that, and the media was intentionally vague to make the story more interesting. My question remains, however- does garlic paste typically cause a false positive? Was the "hit" related to the garlic at all, or was that detail intermixed by the media? I do quite a bit of analytical testing myself and am no stranger to "false" positive (or negative) results, but it helps when interferences are known. As Newark777 mentioned, it's an interesting study- but one with particular public relations and security concerns....

The density of the garlic paste is probably similar to that of some plastic explosives, much like peanut butter and blocks of cheese. The CTX machine will sound an alarm whenever it detects an object of that density. Now there's a couple of ways to solve an alarm and clear the bag. CTX machines have the ability to let you see a 3D image of the bag and the suspect item and sometimes you may be able to clear the bag by looking at it at a different angle. Checkpoint Xray machines have no such ability. The Officer may elect to take the bag and hand search it and ETD swab test the bag to clear it or in this case, after looking at the on screen image, probably noticed the dense Object and some wires or an electronic device that was in the bag and looked as if it was "attached" to the dense object.(garlic paste) I'm just speculating on this as I was not there. The Officer then got a supervisor, who after reviewing the image notified an airport police officer. That police officer then shut down and cleared the area and called for the fire dept. and a bomb sniffing dog. Not the bomb squad. The bomb squad is not always at the airport. They are only there during a code orange or code red terrorism alert and are only called if the dog signals that the bag has explosive residue in or on it. After full inspection of the bag, the TSA officers and the police try to determine what caused the "alarm." In this case the only item in the bag with "correct" density was the garlic paste. The media heard that and went to town. Typically most food items will set off the machine. It just depends on what else is in the bag and how it looks on the screen and that determines how the situation is handled.

Nitroglycerin pills will set it off. My bag gave a false positive in DCA two years ago and the TSA girl became very worried very quickly. Luckily a supervisor yelled at her for using a known broken machine before she could call in the calvary to take me out.

"If you can't delight in the misery of others then you don't deserve to be a college football fan."

Quoting PHLJJS (Reply 6):CTX machines have the ability to let you see a 3D image of the bag and the suspect item and sometimes you may be able to clear the bag by looking at it at a different angle. Checkpoint Xray machines have no such ability. The Officer may elect to take the bag and hand search it and ETD swab test the bag to clear it

OK, that makes sense. I had assumed it was an ETD swab that was triggered, having no info on standard ops at PHL. At many security checkpoints I go through (mostly government facilities) they do the swab test routinely, but I have never seen a false positive on them. (hence the curiosity) I have seen the dogs fail often tho- usually because of fuel or pepper products- and then the bag/person/vehicle in question ends up getting a very thorough hand search.

This incident did not happen at a security chekpoint. It occured in the lobby, in front of the ticket counter with a passenger's checked bag not his carry-on. ETD tests are usually done if the bag is reported to be suspicious by the CTX machine. In this case it seems that after reviewing the image and believing that there may actually be an explosive device in the bag, they called for the police and a dog. I don't believe an ETD was done on this bag.

Quoting PHLJJS (Reply 9):This incident did not happen at a security chekpoint. It occured in the lobby, in front of the ticket counter with a passenger's checked bag not his carry-on. ETD tests are usually done if the bag is reported to be suspicious by the CTX machine.

OK, that makes much more sense to me now. I guess I missed that at first. Thanks!